Debit card is IMHO the best to use anywhere traveling internationally (but always have a little cash backup). Only use the bank ATM's or something at a store like Mega Mart, Hi Lo, etc. She will have the option to withdraw the money in JA or US. I always use the currency of the country I am in.
If they have large sum in their account just setup another account like through a credit union with the amount they expect to spend plus a little more. If they were to use the card some place like a gift shop, restaurant (NEVER DO IT) and someone did a digital copy they would only have access to that smaller amount not their whole bank account.
As someone else mentioned be sure they contact the bank to let the bank know the travel dates and where they will be otherwise they may have no access with the debit card.
